The present invention relates to a method and apparatus for detecting or sensing the position of a container on a conveyor line used in a manufacturing facility that conveys large numbers of containers over short periods of time. More particularly, the present invention is directed to a method and apparatus for detecting whether a container on a conveyor line is misaligned or fallen, and if so, selectively ejecting such container.
The present invention relates to a system for detecting misaligned or fallen objects among other properly aligned objects on a conveyor line. Once an object has been detected as being misaligned or fallen, an ejector arrangement is provided to quickly remove the fallen object.
In many different types of manufacturing facilities, objects, and more particularly containers, are transported along conveyor lines to various processing stations. Normally, the containers are placed on a conveyor in a predetermined, upright position. That is, the container bottom rests on the conveyor when the container is in the upright position. Occasionally, the container may fall or be misaligned on the conveyor. For the purposes of this invention fallen or misaligned containers will be referred to generally as xe2x80x9cdownxe2x80x9d containers. Such down containers may result in jamming of the other containers on the line or may interfere with processing or other material handling operations with upright containers. Accordingly, it is important to detect and remove down containers as quickly as possible before they reach critical processing areas on the conveyor line.
Other types of container detection and ejection systems have been proposed. U.S. Pat. Nos. 3,506,840 to Fink; 4,354,865 to Poad et al.; and 4,494,656 to Shay et al. disclose down-ware rejector systems for removing fallen containers on a conveyor line. These patents teach arrangements for detecting fallen bottles relying on single sensor, such as a reflected light beam or sonic wave. The angle of incidence of the reflected light beam or sonic wave from a fallen bottle is different from an upright bottle. When a fallen bottle is detected, it is ejected using a plunger arrangement.
U.S. Pat. No. 3,710,922 to Lanphere teaches the use of a fiber optic system for detecting misorientation of an object on a conveyor. A light beam is directed toward the object from a fiber optic sensor. If the object has fallen or is misaligned on the line, the light beam will be reflected at a different angle than that from an upright and correctly aligned object. When the system detects a fallen object, it is ejected.
U.S. Pat. No. 3,433,966 to Letch et al. teaches a system using a single top sensor. When a sensor senses a fallen bottle, it actuates an alarm or a device for righting the fallen bottle. While this patent shows several sensors disposed above the containers, each is sensing a fallen bottle in a particular lane. Thus, it teaches the use of a single sensor.
Each of these prior systems suffers various problems. All of the systems rely on a single sensor to determine the orientation of the object on a conveyor line. The use of a single sensor may lead to erroneous detection results based on the orientation or shape of the container. In addition, the detection systems of Fink, Poad, Shay and Lanphere all depend on container geometry to produce a specific angle of reflection. These systems require expensive and complex signal processing circuitry to determine container status.
An object of the invention is to solve the above mentioned disadvantages and therefore to provide an improved container orientation detection system. To achieve these and other advantages, the present invention is directed to an apparatus for detecting and ejecting down containers on a conveyor line that is adapted to move a plurality of containers, each having a top and a bottom. According to a preferred embodiment of the invention, at least three sensors are arranged beside the conveyor, at least two of the sensors being positioned to detect the top of the containers and at least one of the sensors being positioned to detect the bottom of the containers when the containers are in an upright position. Preferably, the sensors are non-contact sensors, although the invention contemplates any suitable type of sensor well-known in the out. Most preferred are optical type sensors, including but not limited to, a radiant light source and photocell, fiber optics or camera type devices. The sensors may also be sonic type sensors. Depending on the configuration of the conveyor line and/or the type of containers, there could be a mix of different types of sensors. The sensors produce a signal which represents the presence or absence of a container portion.
Suitable sensors are photoelectric retro-reflective, photoelectric polarized retro-reflective, photoelectric diffuse and photoelectric polarized diffuse sensors. Additionally, transmitted beam, infrared fiber optic and plastic fiber optic sensors may be used.
A control system is provided for determining whether said containers are down based on the signals produced from the sensors. The control system is preferably a stand alone electronic control apparatus. However, any type of electronic control apparatus that is capable of signal processing may be used.
The present invention also includes an ejector to remove any fallen containers detected on the conveyor. The ejector is actuated by a control signal generated by the control system, based on signals output from the sensors. For down containers that are empty, the ejector is preferably an air jet that blows the fallen container off the conveyor. For heavier, such as full, containers, the preferred ejector is a ram-type pusher. Other well-known types of ejectors are also contemplated, such as robotics. Other types of contemplated ejectors are pneumatic cylinders, pneumatic actuators and solenoid actuated rams.
The present invention is also directed to a method for removing down containers on a conveyor line. The method includes the step of detecting the presence or absence of the tops of containers with at least two sensors as the containers move along on a conveyor. The method also includes the step of detecting the bottoms of containers with at least one sensor. A further step of determining whether a container is in an upright or fallen position based on signals output from the sensors is also included. The method includes a further step of removing any fallen containers based on the determination of whether the container has fallen.